Soft tissues, such as ligaments, tendons and muscles, are attached to a large portion of the human skeleton. In particular, many ligaments and tendons are attached to the bones which form joints, such as shoulder and knee joints. A variety of injuries and conditions require attachment or reattachment of a soft tissue to bone. For example, when otherwise healthy tissue has been torn away from a bone, surgery is often required to reattach the tissue to the bone to allow healing and a natural reattachment to occur.
A number of devices and methods have been developed to attach soft tissue to bone. These include screws, staples, cement, suture anchors, and sutures alone. Some of the more successful methods involve use of a suture anchor to attach a suture to the bone, and tying the suture in a manner that holds the tissue in close proximity to the bone.
The tissue may be attached to the bone during open surgery, or during closed (e.g., arthroscopic) surgical procedures. Closed surgical procedures are preferred since they are less invasive and are less likely to cause patient trauma. In a closed surgical procedure, the surgeon performs diagnostic and therapeutic procedures at the surgical site through small incisions, called portals, using instruments specially designed for this purpose. One problem encountered in the less invasive, closed surgical procedures is that the surgeon has significantly less room to perform the required manipulations at the surgical site. Thus, devices and methods are needed which will allow a surgeon to effectively and easily attach tissue to bone in the small spaces provided by less invasive surgical procedures.
Proper attachment of soft tissue requires that it be placed in the anatomically correct position to promote optimal healing. Conventional methods for attaching soft tissue to bone have typically used toggling anchors having sutures attached thereto. The sutures enable the soft tissue to be adjustably tied down in proximity to the bone surface after the anchor is inserted in a predrilled bone cavity. However, the suture strands extending from the bone anchor can often encumber the area in which the bone anchor is introduced, leading to less than ideal engagement of the anchor in the cavity. In a situation where the bone cavity needs to be larger than the bone anchor to provide clearance for both the suture strands and the anchor, it is difficult to then effect sufficient engagement of the anchor to the bone.
There is thus a need for an improved system for anchoring soft tissue to bone which provides optimal purchase into bone to prevent loosening of the anchor in the bone cavity. Further, there is a need for an improved system for anchoring soft tissue to hard bone which enables suture strands to be located on the same side of the anchor body in order to maximize the area of the leading surface of the bone anchor which engages bone, resulting in increased engagement and resistance to tensile forces. It would also be advantageous to provide a fully absorbable suture anchor and system.